[Note: This offering is best if preceded with the information presented in Indigenous Aquatic Ability: The “Bends”]
Continuing our theme of increased tactical ability on or beneath the waves let’s look to one of the most well-known of indigenous diving cultures, that of the Ama of Japan.
The Ama diving culture has existed for over 2000 years and this longevity provides excellent utilitarian lessons for the modern student of aquatic tactics.
The Ama are sea-harvesters, both above and below the waves. Below the waves the sea-floor is reaped for shellfish, sea slugs, octopus, sea urchins and seaweed. They also dive for Akoya-gai, a mother-of-pearl shell used for pearl cultivation.
In the woodblock prints of Ukioy-e artists we see young women, nude to the waists, harvesting the sea. Flash-forward to the 21st-cetury and we see that this is the exact same practice. The Ama divers [by tradition all women] young and old bare the upper-body and perform their amazing task just as it has been done for centuries.
There are two classes of Ama, the cachido and the funado.
The cachido are usually younger woman going through an apprenticeship. During their “training period” the cachido regularly make unassisted dives to depths of 15-20 feet spending approximately 15 seconds on the seabed per dive. They may make up to 60 dives per hour. The shallow depth and short duration does not induce DCS. [Again, see the aforementioned piece for more on DCS.]
The funado, more experienced divers [often women in their 50s and up] make assisted dives. That is, they have a partner in the boat [typically a non-diving male.] The funado has a mulberry cord tied around her waist, the other end is in the hands of the assistant who remains boat-side. She grasps a heavyweight enters the water in the vertical with legs pressed tightly together to reduce drag and descends to the bottom where she will release the weight and begin harvesting.
Funado regularly makes dives of 60 feet with total breath-holding time of one-minute, half of that is spent on the seabed.
At the end of the dive, she grasps the basket full of harvest and pulls on the mulberry line to be raised.
Once topside, she gasps for air, rests and repeats the performance for approximately 50 times in a morning session and a further 50 in an afternoon session.
The Ama do not suffer from Decompression Sickness [aka “The Bends”] and there may be some reason for that in their method.
One-Dive duration. Shorter dives [approximately one-minute] less time for nitrogen to bubble out of solution.
Two-Rest time topside. They rest for approximately one-minute. This is less than the Mangareva divers [again the previously mentioned article] but the dive-time is a bit less and the depth is a bit less.
Let us also take note that the Ama use the hyperventilating technique covered in a prior article titled AncientHellene Frogmen & Combat Breath-Holding Tactics. [See that article for the how-to.]
The Ama divers are women by tradition but there seems to be no physiological reason why these tactics cannot be adopted by either sex. Women are a bit more cold-resistant in water and can hold their breath a bit longer than men, but, over all, these same diving feats can be performed by either sex as long as the indigenous wisdom of preparation, dive duration, and rest times are followed.
Note: Approximately 60% of funado experience tinnitus or some hearing loss. It is surmised that the volume of diving at depth with the concomitant pressure-changes is the culprit. The Ama do not appear to have a pressure-equalization tactic as part of their cachido apprenticeship.
In the next article in the Aquatic Tactics Series we will address several methods to equalize pressure by other indigenous diving cultures, so we can improve our own performances.
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